France builds world's first stealth wind farm

A French renewable energy corporation is building the world’s first wind farm with turbine blades designed to minimise interference with radar systems.

Inspired by stealth warplanes, undetectable by radars, the design of the blades has been developed by Danish wind turbine maker Vestas and tested at various sites including in the UK.

EDF Energies Nouvelles, a subsidiary of EDF Energy, will install the wind turbines near Perpignan next spring and plans to put them online by the end of 2015.

"It is a world premiere for this new technology," an EDF EN spokeswoman said.

With a combine energy generation capacity of 96 megawatts, the new farm is set to become the largest in France.

The breakthrough design developed by Vestas promises to resolve stalemates between energy companies and air traffic controllers and military, who have been blocking many projects because of possible radar signal interference.

Turbine makers have put years of research into radar signature reduction, most of which is still in the experimental stage.

"We have used surface treatment technologies, including those derived from military applications," said Nicolas Wolff, head of the Danish firm's French unit.

Radar-evading jets such as the Lockheed Martin F-117 Nighthawk use a combination of shapes, angled surfaces and radar-absorbing coatings to mask their radar cross section, a measure of the extent to which they are detectable by radar.

Wolff said that Vestas needed one or two more years of research to study the potential for exporting the technology and that Britain and the United States were possible markets.

EDF EN had previously tested the new technology on two turbines in a wind park in Auvergne, in central France.

In France, close to 6,000 MW of wind farm projects have been blocked because of fear of interference with military or weather radar, French Windfarm Federation (FEE) said.

"There is a conflict here; there are two kinds of users for the same space. For us, it is a real problem," said FEE director Sonia Lioret.

The French army must be consulted about any wind farms planned within 30 km of its radar stations, and is putting up more resistance to new projects, given that the newest turbines can be as tall as 150 metres.

The defence ministry told parliament in July that it needed to ensure "sufficient capacity" for its warplanes to fly at low altitudes, both for defence and training missions.